An image forming apparatus using an electrophotographic method forms a visible toner image on an image carrier by supplying toner to an electrostatic latent image formed on the image carrier, transfers the toner image onto a print medium, and fixes the transferred toner image on the print medium, thereby printing a predetermined image on the print medium.
A developing apparatus is to form a visible toner image on the image carrier, and may include an image carrier, a developing roller for supplying toner to the image carrier and a toner storing portion for receiving the toner. Such a developing apparatus may be formed in a variety of structures such as a monolithic structure in which the image carrier, the developing roller, and the toner storing portion are integrally formed, a separable structure in which the image carrier, the developing roller, and the toner storing portion are separated into at least two units, and the like.
FIG. 1 is a view illustrating a conventional developing apparatus.
Referring to FIG. 1, a conventional developing apparatus 300 includes an image carrier cartridge 310 in which an image carrier 311 is disposed and a developing cartridge 320 in which a developing roller 321 is disposed and toner is received.
The image carrier cartridge 310 includes the image carrier 311 which is rotatably disposed in the image carrier cartridge 310 and a waste toner receiving portion 313 for receiving waste toner.
The developing cartridge 320 includes a developing portion 323 including a developing roller 321 and a supply roller 322, and a toner storing portion 327 including an agitating member 325 and accommodating toner.
The developing roller 321 is rotatably disposed in the developing portion 327 and supplies the toner to the image carrier 311 provided in the image carrier cartridge 310. The supply roller 322 is rotatably disposed on one side of the developing roller 321. A first agitating member 324 is provided above the supply roller 322.
The toner storing portion 327 is provided above the developing portion 323 and supplies the toner to the developing portion 323. A second agitating member 325 is rotatably disposed at the center of the toner storing portion 327. When the second agitating member 325 rotates, one end portion 326 of the second agitating member 325 rotates while contacting almost all the inner wall of the toner storing portion 327. When the second agitating member 325 provided in the toner storing portion 327 rotates, the toner in the toner storing portion 327 is agitated and supplied to the developing portion 323.
The first agitating member 324 provided in the developing portion 323 is formed in an auger shape and supplies fresh toner supplied from the toner storing portion 327 toward the supply roller 322, and carries old toner toward the toner storing portion 327 so that the old toner remaining after development is not stagnated.
In the conventional developing cartridge 320, since the rotation radius of the second agitating member 325 located at the center of the toner storing portion 327 is large, when the second agitating member 325 rotates, the toner in the upper side of the toner storing portion 327 and the toner in the lower side of the toner storing portion 327 are continuously mixed with each other. Therefore, the toner accommodated in the toner storing portion 327 is continuously subjected to physical stress by the second agitating member 325.
Also, since the first agitating member 324 provided inside the developing portion 323 moves the old toner around the supply roller 322 to the toner storing portion 327, the fresh toner and the old toner are mixed in the developing portion 323 and the toner storing portion 327 as whole. Accordingly, since the fresh toner in the toner storing portion 327 is mixed with the old toner recovered from the developing portion 323 to the toner storing portion 327 while being continuously subjected to stress by the second agitating member 325, the life of the toner is reduced. In addition, when an image is formed with stressed toner, an image problem may be caused.
As described above, the conventional developing cartridge is difficult to use in an image forming apparatus requiring a long life because the toner accommodated in the toner storing portion is subjected to a lot of stress.
Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.